There is a way to make them from a single length of fabric; however, it's been several years since I studied that method. I will see if I can find it on the net somewhere. I know I have seen it in more than one book.
......... (time lapse)
Okay, I did a search and came up with this website:
http://tinyurl.com/2dbnlp
When I Googled how to make prairie points I came up with other websites too, but this seemed to have the clearest explanation. While surfing the other sites, I noticed that there are different ways to fold prairie points so they can look different depending on your method.